The present invention relates to an optical detector with a filter layer of porous silicon, with a laterally modifiable filter effect as defined in the introduction to Patent claim 1, and to a method for manufacturing such an optical detector, as defined in the introduction to Patent claim 9.
Many methods for the spectral dispersion of light are known. Examples of such methods are refraction through a prism, diffraction in a linear lattice, or wavelength-dependent reflection or transmission on dielectric filter layers (e.g., Bragg reflector, Fabry-Perot filter). A simple and cost-effective method for manufacturing dielectric filters is to generate super-lattices of porous silicon. At The same time, as a starting material, silicon offers the possibility of generating photoreceptors (e.g., photoresistors, photodiodes).
To the extent that semiconductor-based photodetectors, the use of superlattices of porous silicon, and the production of lateral process filters are known, up to now all known detectors entail the disadvantage that they can hardly be modified. Using the methods that are known, it is only possible to manufacture detectors that can be used in a range of wavelengths that is established by this process. In addition, the complete filter layer is not used for detection, or the individual wavelength ranges cannot be completely decoupled from each other.
For this reason, it is the objective of the present invention to create an optical detector that can be manufactured in a simple and cost-effective way, and that is modifiable. In addition, it is intended to describe a manufacturing method for such an optical detector, with which the filter properties, i.e., the variability of the detector, can be adjusted in a simple manner.
According to the present invention, this objective has been achieved by an optical detector with the distinguishing features set out in Patent claim 1, and by a manufacturing method having the distinguishing features set out in Patent claim 9.
Contact surfaces and active filter regions can be predetermined by the integrated configuration, using lithography only once.
According to claim 2, it is an advantage that the contacts are arranged transversely to the filter layer, since individual detectors that are adjacent to each other can be almost completely decoupled from each other by so doing, although the filter area is reduced if this is done.
According to claim 3, in order to obtain a large filter area, it is an advantage that the contacts are attached at the sides of the filter layer. Because of this, the whole of the filter layer can be used for detection, although the individual wavelength ranges cannot be completely decoupled from each other if this is done.
Additional advantages of the present invention are set out in the secondary claims 1 to 8 and 11 to 16.